Phenylation of methacrylic acid



li atented cr. is, 951 2,571,639

PHENYLATI N F METHACRYLICACID Immanuel iEvanstomr and Marvin A.

Spielman, Waukegan, 111;, assignors'to Abbott I f Labo'ratories, North Chicago; 111.; a corporation elf-Illinois I w xi (:L'

No DrawingQAppliication Decemberfil), 1949, 1 f b Serial No.1? 4,1 36 f I 10 c a ms; (omen-515) This invention relates. to a process "for "the ture temperature is raised to reflux temperature phenylation of methacrylic acid, and more par- '(abo'ut'82;C.)' for'about '4 hours with continu'ed ticularly is directed to a method for phenylatstir-ring. I At the end of-the refiux-period I the ing the a-carbon atom-of methacrylic acid in I mixture is lcooled and poured on an ice-concenthe presence of a catalyst. I I a v l 5 trated hydrochloric acid-'mi'xture -(as-per Ex- The phenylation of methacrylate esters in the ample I). The two layers which are formed are presence of aluminum chloride catalyst produces separated, and the be'nzenelayer is washed with a new and unexpected result as the-phenyl ring water. The benzene is removed'from the hen-'- is added to the alpha carbon atom insteadof zene phase by.vacuum' distillation. The-residue the predicted beta position' By. using .anlester l0 isidistilled at mm.0f mercuryv and theproduct, of methacrylic acid derivedfrom-an alcohol of methyl o-phenylisobutyrate, is recovered-as ,a two or more carbon atoms, c phenylisobutyric fraction that-distills at 103-106? C. o-Phenylisoacid is obtained directly. 1 butyricacidmay be recovered by alkalihydrolysis In generaL'the process'of the invention is perof the methyl a-phenylisobutyrate. r a formed by reacting an alkyl ester methacrylate l5 1 1 i with benzene in the presence of a catalyst.- Eimmple H A In e p fi detail, the process of the Following the procedure of Example I, 1.8 mols vention y be illustrated y thelfollowing of anhydrous benzene, 0.3 mol of n-butyl metha p acrylate, and 0.53 mol of anhydrous aluminum Example I chloride are allowed to react, and c-phenyliso- To about 3 mols of ethyl methacrylate disbutync acld is recovered solved in about 26 mols of dry benzene, is added Emzmple 1V about 5.25 mols of anhydrous aluminum chloride with'constant stirring. During the addition of the aluminum chloride, the temperature of the mixture is kept around 5560 C. After the addition of the aluminum chloride is completed, the temperature of the reaction mass is kept at The temperature of the reaction of the meth t? 60 for abput. wlth constant acrylate benzene in the presence of aluminum stlrrmg' The reacnon mlxture then poured chloride should be maintained between 40 C into about 100 mols of ice-9 mols hydrochloric and the reflux temperature, which is about 82 C: f mlxtute' The addltwn to the we i i Obviously, the lower the temperature the longer is done Wlth cons/Pant and thorough surfing the time of reaction, and conversely, the higher The two layers winch form i Separated and the temperature the less time of reaction is rethe benzene layer 13 washeq Wlth about 100 mols quired. It is not desirable to carry out the reof water The benzene 1S y q t the action below C. as the time of reaction would non-aqueous fraction by vacuum distillation, and be prohibitably 1ong the residue is cooled. The precipitate which The catalyst aluminum chloride, is used in is formed is filtered out and is dissolved in 10% 4O amount of 125 to 2 mols per mol f the meth Sodmm Y the solunon l acrylate. The desired ratio is 1.75 mols of alu- The alkaline solution is then carefully acidified minum chloride per mol of the methacrylate with hydrochloric acid and the precipitate which Below the one molar ratio the desired reaction forms is filtered out and dried. The product is does not occur 'phenyhsobutync 301d, memng pomt 72-73 The catalyst required for the reaction must be E 16 H a strong 'electrophilic catalyst such as aluminum chloride, boron trifluoride, hydrofluoric acid, etc. To about 9 mols of methyl methacrylate dis- Weaker catalysts such as ferric or zinc chloride solved in about 68 mols of dry benzene, are added ill not catalyze the reaction, S W y and w Constant Stirring 15-75 111018 of Others may readily adapt the invention for use anhydrous aluminum Chloride- The addition of under various conditions of service, by employing the aluminum chloride should take pl c v a one or more of the novel features disclosed or period of about 3 hours, and the temperature equivalents thereof. As at present advised with kept at about 60 C. After the completion of the respect to the apparent scope of our invention, addition of aluminum chloride, the reaction mixwe desire to claim the following subject matter.

Following the procedure of Example I, 1.8 mols of anhydrous benzene, 0.3 mol' of n-octyl methacrylate, and 0.53 mol of anhydrous aluminum chloride are allowed to react and the mixture is worked up to produce aphenylisobutyric acid.

We claim:

1. In the process of phenylating the a-carbon atom of methacrylic acid, the step which comprises reacting an alkyl ester of methacrylic acid with benzene in the presence of a catalyst selected from the class consisting of aluminum chloride, boron trifluoride and hydrofluoric acid.

2. In the process of phenylating the a-carbon atom of methacrylic acid, the stepwhich comprises reacting an alkyl ester of methacrylic acid with benzene in the presence of aluminum chloride.

3. In the process of phenylating the a-carbon atom of methacrylic acid, the step which comprises reacting an alkyl ester of methacrylic acid with benzene in the presence or aluminum chloride, at a temperature of at least about 40 C.

4. In the process of phenylating the a-carbon atom of methacrylic acid, the step which comprises reacting an alkyl ester of methacryiic acid, in which the ester radical contains from i to 8 carbon atoms, with benzene in the presence of at least about 1.25 mols of aluminum chloride per mol of the methacrylic acid ester, said reaction being carried out at temperature of at least about 40 C.

5. The process of producing m-phenylisobutyric acid which comprises reacting ethyl methacrylate with benzene in the presence of at least about 1.25 mols of aluminum chloride per mol of the'methacrylate.

6. The process of producing a-phenylisobutyric acid which comprises reacting butyl methacrylate with benzene in the presence of at least about 1.25 mols of aluminum chloride per mol of the methacrylate.

'7. The process of producing u-phenylisobutyric acid which comprises reacting octyl methacrylate with benzene in the presence or at least about 1.25 mols of aluminum chloride per mol of the methacrylate.

8. The process according to claim 5 which reaction is carried out at a temperature of at least about 40' c.

9. The process of producing a-phenyiisobutyric acid which comprises reacting methyl methacrylate with benzene in the presence of catalytic amounts of aluminum chloride, and the hydrol-- ysis of the resulting methyl a-phenylisobutylate. 10. The process of producing a-phenylisobutyric acid which comprises reacting methyl methacrylate with benzene in the presence of at least about 1.25 mols of aluminum chloride per mol of the methyl methacrylate at a temperature of at least about 40 C., and hydrolysis of the resulting methyl a-phenylisobutylate to form the a-phenylisobutyric acid.

IMMANUEL J. WILK.

MARVIN A. SPIELMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,246,762 Schirm June 24, 1941 2,275,312 Tinker et al Mar. 3, 1942 2,475,916 Reifi et al. July 12, 1949 OTHER REFERENCES Koelsch et al., J. Am. Chem. Soc., vol. 65, pp. -60 (1943). 

1. IN THE PROCESS OF PHENYLATING THE A-CARBON ATOM OF METHACRYLIC ACID, THE STEP WHICH COMPRISES REACTING AN ALKYL ESTER OF METHACRYLIC ACID WITH BENZENE IN THE PRESENCE OF A CATALYST SELECTED FROM THE CLASS CONSISTING OF ALUMINUM CHLORIDE, BORON TRIFLUORIDE AND HYDROFLUORIC ACID. 